UN aid chief Stephen O'Brien attends a news conference at the United Nations in Geneva, Switzerland, September 9, 2016. (Photo by Reuters)

The United Nations has expressed disappointment at the delay in delivering humanitarian aid to the embattled Syrian city of Aleppo, where civilians are suffering from the lack of food and emergency relief.

Speaking at a press conference on Monday, the UN aid chief said he was “pained” that the Aleppo residents were still without food and water, after reports said that an aid convoy was being stalled on the Turkish-Syrian border for a week.

"I am pained and disappointed that a United Nations convoy has yet to cross into Syria from Turkey, and safely reach eastern Aleppo, where up to 275,000 people remain trapped without food, water, proper shelter or medical care," Stephen O'Brien said.

According to the UN official, the convoy consists of 20 trucks that carry flour and other food supplies, enough to feed some 185,000 people for one month.

Syrians pass through rubble in the neighborhood of Karm al-Jabal in Aleppo, Syria, on September 18, 2016 (Photo by AFP)

The remarks came after a week-long ceasefire in Syria expired at midnight, with no immediate announcement of its extension.

Russia and the US agreed on the ceasefire deal in Syria on September 9 after intensive talks in the Swiss city of Geneva.

The seven-day deal, which began on September 12, calls for increased humanitarian aid for those trapped, especially inside the northwestern city of Aleppo, Syria's second largest city which has been divided between government forces and foreign-backed militants since 2012.

The Syrian government has accused foreign-backed militants of numerous violations of the ceasefire, the second this year.

Syria has been gripped by foreign-backed militancy since March 2011.

Over the past few months, the militants active in the Arab country have suffered major setbacks as the Syrian army has managed to liberate several areas.

According to an estimate by UN Special Envoy for Syria Staffan de Mistura, more than 400,000 people have been killed in the conflict in Syria.